I saw the same results in the traces I sent Sumit yesterday.  What I'm coming to believe, is that this chart:

 

 

From here https://techcommunity.microsoft.com/t5/core-infrastructure-and-security/ldap-channel-binding-and-ldap-signing-requirements-march-update/ba-p/921536

 

Seems to show that regardless of how the domain is set, i.e. requiring signing or not, if you’re employing local encryption, via GSSAPI, or SSL, the connection will succeed.  And is technically encrypted, so satisfies the security requirements, but Microsoft still logs on the domain that the connection was made without signing.

 

Admittedly, that’s not what, I think, everybody expected to happen when you “Require signing” on the domain and you don’t sign on the client.  I would have expected connections to fail at that point.  But given that GSS-SPNEGO is only available on RHEL 7.2ish + and not on RHEL 6, and likely similarly aged distros, requiring signing, and not allowing that 5th option would have basically broken an entire operating system, or more.  I also suspect that Macs are in a similar state.  Using the -ssl switch on the dsconfigad utility sets it to “line 4” in the chart, but requires, just like it would for RHEL additional certificates be made available to every install.  I have seen similar commands for dsconfigad like, dsconfigad -packetsign require, but it’s only available in 10.5 and later, which is probably about the time GSS-SPNEGO was added to RHEL 7, I suspect.

 

So when I look in splunk and have it count the number of unsigned binds in the last 24 hours and see a number like 2,518,239.  I can’t assume that all those are insecure.  What I can’t tell from that is how many of those are using GSSAPI or SSL, because they are logged as unsigned whether they use it or not.

 

Awesome.

 

Todd

 

 

 

-----Original Message-----
From: James Ralston <ralston@pobox.com>
Sent: Thursday, February 13, 2020 3:50 PM
To: End-user discussions about the System Security Services Daemon <sssd-users@lists.fedorahosted.org>
Subject: [SSSD-users] Re: sssd 1.16.4. ADV190023.

 

On Thu, Feb 13, 2020 at 10:24 AM Mote, Todd <moter@austin.utexas.edu> wrote:

 

> Only using GSSAPI causes the unsigned SASL event.

> 

> root@anti-test:~ # ldapsearch -H ldap://dc01a.ADTEST.domain.com -Y

> GSSAPI -b '' -s base SASL/GSSAPI authentication started SASL username:

> ANTI-TEST$@ADTEST.domain.com SASL SSF: 256 SASL data security layer

> installed.

> # extended LDIF

> #

> # LDAPv3

> # base <> with scope baseObject

> # filter: (objectclass=*)

> # requesting: ALL

> 

> GSS-SPNEGO looks the same, and does not trigger the unsigned event.

> 

> root@anti-test:~ # ldapsearch -H ldap://dc01a.ADTEST.domain.com -Y

> GSS-SPNEGO -b '' -s base SASL/GSS-SPNEGO authentication started SASL

> username: ANTI-TEST$@ADTEST.domain.com SASL SSF: 256 SASL data

> security layer installed.

> # extended LDIF

> #

> # LDAPv3

> # base <> with scope baseObject

> # filter: (objectclass=*)

> # requesting: ALL

 

We see the exact same thing on our RHEL7 hosts.

 

Looking at the packet traces of "-Y GSSAPI" and "-Y GSS-SPNEGO", both connections issue the query under SASL GSS-API Privacy.  But with GSSAPI, it takes 3 steps to complete the bind request and activate SASL GSS-API Privacy:

 

    bindRequest(1) "<ROOT>" sasl

    bindResponse(1) saslBindInProgress

    bindRequest(2) "<ROOT>" sasl

    bindResponse(2) saslBindInProgress

    bindRequest(3) "<ROOT>" sasl

    bindResponse(3) success

    SASL GSS-API Privacy: payload (148 bytes)

    SASL GSS-API Privacy: payload (160 bytes)

    SASL GSS-API Privacy: payload (7 bytes)

 

With GSS-SPNEGO, it takes only one step:

 

    bindRequest(1) "<ROOT>" sasl

    bindResponse(1) success

    SASL GSS-API Privacy: payload (148 bytes)

    SASL GSS-API Privacy: payload (160 bytes)

    SASL GSS-API Privacy: payload (7 bytes)

 

Our Windows admins confirm that the GSSAPI query triggers this warning:

 

    The following client performed a SASL

    (Negotiate/Kerberos/NTLM/Digest) LDAP bind without requesting

    signing (integrity verification), or performed a simple bind over

    a clear text (non-SSL/TLS-encrypted) LDAP connection.

 

…but the GSS-SPNEGO query does not.

 

Sumit, in a moment I'll reply just to you, and include the packet traces.

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